Impacts of Sonar on Marine Mammals
Underwater noise resulting from submarine sonar can have serious impacts on marine mammals, specifically the largest clade of cetaceans - whales, dolphins and porpoises. The U.S. Navy strategically plans sonar operations to minimize impacts to these animals. However, research was needed to set the appropriate legal and policy thresholds minimizing stress to these animals. In coordination with Naval efforts, SERDP issued an FY 2011 Statement of Need (SON) focused on addressing the knowledge gaps on the baseline behaviors of these fascinating creatures in order to better understand how anthropogenic sound may alter their normal patterns such as prey avoidance or breeding.
In recent weeks, three SERDP-funded projects from the FY 2011 SON were completed and their final reports are now available for download on the SERDP-ESTCP website. A brief summary of these projects follows.
Dr. Andrew Reed and his team at the Duke University Marine Lab ( RC-2154) examined the baseline behavior of four species of toothed whales (sperm, beaked, killer, dolphins & porpoises) to a predatory species, the same reaction whales have to sonar. By attaching digital acoustic tags to whales, exposing them to the sounds of a predator and examining their vocal and behavioral responses, researches will be able to improve understanding of certain anthropogenic sounds. Varied social structures were incorporated in the design of this study.
Dr. Diane Claridge and her team at the Bahamas Marine Mammal Research Organisation ( RC-2114) investigated the foraging and behavioral ecology of six deep-diving DoD priority species in The Bahamas to fill key data gaps for these species. By studying sonar exposure at a Naval undersea test facility, their findings can lead to improved monitoring and mitigation where exposures occur.
Dr. Kelly Benoit-Bird and her team at Oregon State University ( RC-2112) explored the mapping the prey fields of deep diving whales (sperm and beaked species) which feed on fast moving squid. In the past, that had made studying their large biological feeding habitat difficult. However, recent advances in acoustic measurements enable remote sensing tools to more effectively assess squid behavior and therefore the prey field and occupancy patterns off the whales. Understanding the link between the prey field and whale behavior will inform modeling efforts going forward.
Other ongoing cetacean research sponsored by SERDP and ESTCP includes:
- Dr. Patrick Miller and his team at the University of Saint Andrews examining how noise may reduce foraging rates and therefore body density and reproductive status in Northern bottlenose and humpback whales ( RC-2337).
- Dr. Cara Hotchkin and her team at NAVFAC Atlantic are determining if passive acoustic detectic of baleen whales is a suitable replaced to currently utilized visual and acoustic monitoring efforts employed by the Navy ( RC-201446).
- Dr. David Moretti and his team at the Naval Undersea Warfare Center are integrating real-time sonar detection and GPS into whale monitoring in order to determine whale reactions ot Mid-Frequency Active (MFA) sonar operations ( RC-201304).
Photo credits: Joanna Kershaw, Sea Mammal Research Unit, University of St Andrews